There is a fundamental gap in understanding how young children change the many mistaken beliefs they hold about every-day physical phenomena. The long-term goal then is to identify evidence-based instructional interventions to promote such change. However, before this goal can be attained, the basis of young children's intuitive physics needs to be unraveled. Recent findings suggest that children's beliefs are constrained by other beliefs they hold, in that children strive toward a congruent configuration among their beliefs. The objective of the present R03 application is to investigate the nature of this bias toward congruent beliefs. The central hypothesis is that children actively strive toward congruent beliefs about physical phenomena, as a way of making sense of the world. Guided by preliminary data, this hypothesis will be tested in three specific aims: (1) Examine how children's bias toward congruence progresses as a function of age;(2) Examine the generality of children's bias toward congruence across domains and tasks;and (3) Explore ways of correcting children's errors that come out of their bias toward congruence. Under specific aim 1, an already established approach of testing children's bias toward congruence will be used across a wide range of ages. Under specific aim 2, children's bias toward congruence will be tested in different content domains and with different types of tasks. Finally, under specific aim 3, an intervention will be tested that shifts children's attention away from superficial and misleading congruence, and therefore circumvents mistaken beliefs that come out of this bias. The overall approach offers a fundamentally different picture of young children's naive physics, because it links young children's mistakes to adaptive principles of knowledge organization. The objective of this application to understand how children's bias toward organizing their knowledge leads to mistakes is an under-investigated area of child development. It is translational research with direct implications for elementary and secondary instruction in science, because it addresses what it would take to more effectively improve children's learning of physical concepts. On a more global level, the application has implications for our understanding of children's mental health, because the tendency to organize knowledge and the mistakes associated with this tendency are a sign of normal development.